Add imu hint to detect multiple planes

Detect multiple planes with hint from IMU
![screenshot_from_2014-11-03 23 06 11](https://cloud.githubusercontent.com/assets/40454/4883547/ce9a67f6-6362-11e4-87a7-9274b4c4441c.png)
![screenshot_from_2014-11-03 23 06 29](https://cloud.githubusercontent.com/assets/40454/4883548/cec11428-6362-11e4-92dc-3c0443cd85ca.png)